Custom Field Fileupload Empty in Backend

Hey there,

we added custom fields (fileupload) to our single places and it all worked.
When I open up the place in backend the fileupload field is empty but the database has already the correct path to the file. When I save the post again, the image disappears from the frontend and the database.

Is there a way to resync the database? I did not find any Option in the settings.

Best regards and thanks in advanced
Thomas